In order to add desired characteristics to a cellulose-containing fabric, the cellulose-containing fabric is treated with cellulase. For example, treatment with cellulase is carried out in the field of textile industry for the purpose of improving the touch and appearance of a cellulose-containing fabric or adding a “stone wash” appearance which provides a localized variation in color of colored cellulose-containing fabrics (European Patent 307,564).
Currently, cellulase preparations derived from wood rotting fungi Trichoderma and Humicola are used for the purpose of adding stone wash appearance to dyed-denim cellulose-containing fabric and improving the touch of the same. These cellulase preparations are mixtures of plural cellulase components. Their practical use has been hindered by a difficulty resulting from the necessity to use a large amount of the cellulase preparation for exerting desired effect on the cellulose-containing fabric.
Such a disadvantage of the cellulase preparation is being improved by using a preparation which contains a large amount of endoglucanases. For example, cellulase preparations having enriched endoglucanase activity are published by international publications WO 89/09259, WO 91/17243, WO 98/03640 and WO 94/21801. Particularly, WO 91/17243 discloses that a purified 43 kD endoglucanase component (EGV) derived from Humicola has a jeans abrasive activity which is about 100 times higher than that of a conventionally known cellulase preparation as a mixture of a plurality of cellulase components. Also, WO 98/03640 discloses that an endoglucanase component NCE4 derived from Humicola has a 25 times higher jeans abrasive activity and 100 times higher lyocell fuzz removing activity in comparison with a conventionally known cellulase preparation as a mixture of a plurality of cellulase components.
Such a treatment with cellulase has been carried out with the aim of adding stone wash appearance to a dyed-denim cellulose-containing fabric and improving the touch of the same, but in that case, it causes problems such as redeposition or redyeing of a portion of indigo dye on clothing, namely back-staining, during the treatment process.
There is a method as an attempt to lower degree of the back-staining, in which indigo dye is dispersed in a cellulase treating solution by adding a reagent such as a surfactant. However, this method has problems in that it requires a cost for the adding chemical product and increases environmental load of waste water.
Accordingly, concern has been directed toward the provision of a cellulase having high activity but low degree of back-staining, to be used in the treatment of dyed-denim cellulose-containing fabric.